
class Card(object):
    def __new__(cls, *args, **kwargs):
        # 每一次实例化的时候，都只返回instance同一个对象
        if not hasattr(cls, "instance"):
            cls.instance = super(Card, cls).__new__(cls)
        return cls.instance

card1 = Card();
card1.passward = "66666"
card2 = Card();
print(card2.passward)
print(card1 is card2)
